Process of producting gases by pyrolysis



May l1, 1954 F. w. HARRIS 2,678,339

PROCESS oF PRonUcING GASES BY PyRoLYsls Filed May 5, 1951 2 Sheets-Sheet 2 T /a `A -zo l f.- L f G b 4/ 44? 4Z FUEL GHS HH? OFF-GHS je 33 5o D/LUENT 46 35 STACK `STOCK GHS /N VEN Tof?.

i FORD W. HHH/ws BY HIS HTTORNEKS.

. HAR/ws, K/ECH, FOSTER cHHRR/s *Y 3v Patented May 11, 1954 UNITED sTATEs ATENT oEElcE PROCESS OF PRODUCING GASES BY PYROLYSIS Ford W. Harris, Los Angeles, Calif., assignor to Wullf Process Comp any,

Huntington Park,

2 Claims. 1

My invention relates to the pyrolysis of gases fand it is an object of my invention to provide a lining, the two top masses being placed on either side of the vertical axis of the T in the top bar thereof and the other central mass being placed below the bar in the vertical portion of the T.

(b) The furnace has a central combustion space above the central mass and between the top masses.

A'(c), The furnace has three end spaces each situated at the outer end of one of the three masses, each end space communicating through open channels in its associated mass with said central combustion space.

(d) Each of the end spaces has an end pipe through which gas may be withdrawn from or introduced into the end space.

The process is a cyclic one in which an off-gas containing a substantial proportion of acetylene is formed by the pyrolysis of an in-gas containing a substantial proportion of a suitable hydrocarbon. The word "pyrolysis is usedvin its common, or dictionary, sense as meaning any method of causing chemical changes by the application of heat. The term in-gas denotes any gas or mixture of gases which is to be subjected to i pyrolysis, and the term off-gas denotes gas that has been so subjected to pyrolysis. A substantial proportion of any specific gas in a'mixture of gases means a proportion of at least two per cent (2%) by weight of the specific gas. YThe term suitable hydrocarbon includes all hydrocarbons known to the art at the time this application was filed as suitable for the production of acetylene by pyrolysis. Methane and the olens which are gaseous at atmospheric tempera- 4 passed through channels in a regenerative mass until a portion of said mass is at a temperature substantially above the reaction temperature oi' the pyrolysis;

(f) Thereafter during the make step anin-gas is passed through said channels in said mass, in a direction opposite to that of the flow in the heat step, said flow of in-gas being discontinued before the hottest portion of said mass falls below said reaction temperature.

(y) The heat required for heating said air and gas during the heat step is supplied by regeneration of heat extracted from the off-gas during the make step.

More specific statements as to the novelty and utility of the furnace and process will appear in the following specification.

In the drawings, which are for illustrative purposes only: i

Fig. l is a vertical central section. on a plane indicated by the line I-I of Fig. 2, of a furnace embodying my invention;

Fig. 2 is an end view of the furnace;

Fig. 3 is a section which is identical on all three planes indicated by the lines 3--3 of Fig. l; and

' Fig. 4 is a diagram of pipe connections.

The furnace I0 illustrated in these drawings consists of a tight shell II preferably formed of stainless steel and having a heat refractory and heat insulating lining I2. Placed inside the lining are three regenerative masses I3, M and I5. These masses are disposed in T relationship, the two top masses I3 and I4 being in the bar of the 'T and the third mass I5 being in the stem of the T. The masses I 3 and It are separated by a combustion space I6 and the third mass I 5 is placed below the combustion space I6. All three masses have open' channels l1', as shown in Fig. 3, through which gases may pass into or out of the combustion space It. Three separate end spaces IS,` i9 and 2i) are provided, each end space being placed inside an extension of said shell in such a position that the gases from the channels I1 in one of said masses may pass into or out of said space. An opening 2l closed by a removable cover 22 is provided in the top of the furnace, to enable a torch to beused to preheat the furnace. Outlet pipes 23, 213 and 25 are provided, one each for each of the end spaces i8, I9 and Eil, The furnace is supported on a structural iron framework 25. It is an essential feature of the invention thatfthe masses I3 and I'are supported on their sideson opposite sides of the combustion space It andjthey mass [Isis below this space I5.' because the mass I5 must be supported on its cooler end, which is the lower end. The above described furnace may be used for many purposes but it may be used for the pyrolysis of hydrocarbons if the pipes and valves shown in Fig. 4 are supplied. The valves may be conveniently numbered 30 to 37, inclusive.

Fuel gas is supplied to the pipe 23 through the valve 30 `from a fuel gas pipe 4I. Air or oxygen may be supplied from an air pipe 42 through the valve 31 to the pipe 25. Off-gas may be taken from the pipe 25 through the valve 3S into the off-gas pipe 43. Off-gas may also be delivered from the pipe 23 through the valve 3| to a pipe 44 and thence to the off-gas pipe '43.

Spent `products oi combustion may be taken from the pipe 24 through the valve 32 and passed to a stack through a stack pipe 4'I. A'stockgas. may be delivered from a pipe 45 through the valve 33 to the pipe 24, and this stock gas may be considered the in-gas for the process, taken -alone or mixed :with diluent delivered tothe pipe u45 through a valve 35 'from a pipe 43. In some cases'air or oxygen may be kmixed with the stock gas with or without diluent, the air or oxygen being delivered to the pipe 45 from avpipe 48 through `the valve 34. The in-gas will then consist of stock gas, diluent and air.

An oir-gas pump 53 pulls off -gas from-the pipe 43 and a stack pump 5I pulls spent products of combustion from the pipe 4'I. The above arrangement of valves and piping is well adapted to conduct a recurrent cyclic process consisting of a heat step, in which products of combustion are passed downwardly through channels I'! in the third mass I5, `and a make step in which an in-gas is `passed'upwardly through the channels il.

Prior to starting cyclic operation, `the furnace mustbe preheated which Iis accomplished as follows: The cover 22 having been removed, the

pump 50 is started, the valves 3l and 36 are opened and a burning torch is inserted into the combustion space I6. The products of combustion from the -torch are drawn outwardlyfrom the combustion space through the channels II in the mass I3 and into the end space from which.

they are drawn through the pipes 23, 44 and 43 into the pump 50 andwasted vto the air. The mass 'I3 is thus heated and this heating must be continued until the ends of the masses I3 and yI4 which abut on the combustion space I6 are heated to a temperature very substantially above reaction temperature, which is hereby defined as thelowest temperature at which the desired reaction of the in-gas will readily occur. The heat is so supplied that the inner'ends of `the masses arecuite hot andthe outer ends are much colder. The preheating step is then stopped by withdrawing'the torch and putting the cover 2.2 on the opening 2 i The heat stepis then started by opening the valves 30, 3'I and 32, the pump 5I being also started. Air is thenv drawn into the combustion space I6 through the channels I1 in the mass i4 from the end space 20, this air being supplied through'the pipe 25 and the valve 37 from the pipe'42. Fuel gas, which may or may not be the stock gas, or which may be a waste by-product gas produced in the process, iiows into'the combustion space I6 through the channels I7 in the mass I3 from the end space 13, this gas being delivered to the endspace vI8 through the pipe 2 3v and valve 30 from the vpipe-4I. Both the airand iuelgas are delivered at ahigh temperature and high velocit-yinto thecombustion space I5 where they formproductsof combustion which are drawn downwardly through the channels I1 in the third mass I5 into the end space I9 and from that end space through the pipe 24, the valve 32, and the pipe 41 into the pump 5I from which they are discharged into the stack. During the heat step the masses I3 and I4 give up sensible heat to the air and fuel gas and are themselves cooled and the third mass I'5 cools the products of combustion and is heated by these products. At the conclusion of the heat step, the top'of the mass I5 will be substantially above reaction temperature, which may be as high as 2600" F., while the bottom of the mass I5 may be at a -temperature as lowas 400 F. The inner ends of lthe masses I3 and I4 may be at a temperature even below reaction temperature and the outer ends, due lto the cooling action of the air and fuel gas, may be at a temperature as low as 400 F. The heat step is stopped by closing the valves 30 and 31.

The make step is started by opening the valves 33 and perhaps 34 and 35 so as to supplyin-gas vto the pipe 24. The valves 3| and 36 are opened. The pumps 50 and 5I are continuously running during the cyclic operation and the .pump 50 pulls off-gas from each of the end spaces I8 and Z6 through the pipes 23 and 25, the valves 3| and 36 and the pipes 44 and 43. This gas is off-gas formed in the central combustion space I6 and cooled in the masses I3 and I4. If airis mixed 'with the iii-gas by opening the valve `34, combustion may occur during the make cycle, but preferably only a diluent such, for example, vas steam admitted through the valve 35 -is added to the stock gasfto form'the in-gas. Whenfthe make step is sooperated Without combustion or partial combustion, the heat necessary to produce 4the desired reaction is supplied wholly by heat previously absorbed bythe regenerative masses I3, I4 and I5A The operation of the process will be better understood from the following examples.

Example 1,-Propcne cracking During the heat period, which continued for about one minute, a fuel gas was fed through the mass I3 and more than -enoughair to entirely burn all the fuel gas was'fed through `the mass -I 4. The masses -I 3 and I4 vwere heated by theprevious heating step and both the air and gas entered the combustion space I6 at a temperature somewhat above 2000 F. The products of combustion, with some excess air and at a temperature somewhat below 3000 F., passed downwardly through the third mass irand the heat stepwas continued until the top of the mass i5 was Yat a temperature of about 2600F. The outer ends of the `masses i3 and I4 were ata temperature ci about 250 F. at the end of the heatstep, having been cooled by the entering air and'fuel--gas The in-gas, consisting of propane diluted with four and one-half times (4l/2) its volume of steam passing up through the channels I'I in the mass I5, was heated to a reactiontemperature of about 2200 Ebefore reaction occurred. Thereaction absorbed heat from the regenerative masses and the off-gas formed by the reaction was cooled to about 500 F. as rit passed'outwardly through the masses I3 and I4.

Theoif-gas had about the following composition:

C3116 0.9 CsHs 1.1 O2 and N2 0.3 H2 43.5 CO 2.7 CH4 20.4: C2H6 0.2

It will be seen that after the acetylene was withdrawn from the above off-gas, an excellent fuel gas remained. This gas was in excess of the amount needed to supply fuel gas tothe pipe 4| and was used ,to operate gas-driven compressors used in the separation of the acetylene from the off-gas.

Example 2.Meih,ane` cracking Per cent C2H2 '7.8 CO 8.1 CO2 1.1 CH4 17.3 H2 63.6 N2 1.2

It will be noted that after the acetylene C2H2 was taken out of the off-gas, there was a fuel gas consisting predominately of CO, CH4 and H2 which had a high fuel value.

I claim as my invention:

1. A process of producing an off-gas contain ing a substantial proportion of a desired hydrocarbon from an in-gas containing a substantial proportion of a suitable hydrocarbon, which consists of a preheating step and cyclic process consisting of heat and make steps, said steps being defined as follows: in the preheating step hot gases of combustion are passed from a cen.- tral combustion space outwardly through channels in a first and a second regenerative mass; in the heat step a fuel gas is passed inwardly through the channels in said first regenerative rnass into said central combustion space, air is passed inwardly through the channels in said second regenerative mass into said central combustion space, and the gases of combustion formed by the burning of said fuel with said air n said space are passed through channels in a third regenerative mass; and in the make step the inegas is passed through said channels in said third regenerative mass into said central combustion space and off-gas from said central combustion space is passed through the channels of either the first or the second regenerative mass.

2. A process as in claim 1in which the offgas is passed through the channels in both the first and second regenerative masses.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,940,209 Fischer et al Dec. 19, 1933 2,191,510 Whitehurst Feb. 27, 1940 2,208,123 Duncan July 16, 1940 2,319,679 Hasche et al May 18, 1943 2,421,744 Daniels et al June 10, 1947 2,432,885 Hasche Dec. 16, 1947 2,491,518 Riblett Dec. 20, 1949 2,518,688 Hasche Aug. '15, 1950 FOREIGN PATENTS Number Country Date 572,393 Germany Mar. 25, 1933 

1. A PROCESS OF PRODUCING AN OFF-GAS CONTAINING A SUBSTANTIAL PROPORTION OF A DESIRED HYDROCARBON FROM AN IN-GAS CONTAINING A SUBSTANTIAL PROPORTION OF A SUITABLE HYDROCARBON, WHICH CONSISTS OF A PREHEATING STEP AND CYCLIC PROCESS CONSISTING OF HEAT AND MAKE STEPS, SAID STEPS BEING DEFINED AS FOLLOW: IN THE PREHEATING STEP HOT GASES OF COMBUSTION ARE PASSED FROM A CENTRAL COMBUSTION SPACE OUTWARDLY THROUGH CHANNELS IN A FIRST AND A SECOND REGENERATIVE MASS: IN THE HEAT STEP A FUEL GAS IS PASSED INWARDLY THROUGH THE CHANNELS IN SAID FIRST REGENERATIVE MASS INTO SAID CENTRAL COMBUSTION SAPCE, AIR IS PASSED INWARDLY THROUGH THE CHANNELS IN SAID SECOND REGENERATIVE MASS INTO SAID CENTRAL COMBUSTION SPACE, AND THE GASES OF COMBUSTION FORMED BY THE BURNING OF SAID FUEL WITH SAID AIR IN SAID SPACE ARE PASSED THROUGH CHANNELS IN A THIRD REGENERATIVE MASS; AND IN THE MAKE STEP THE IN-GAS IS PASSED THROUGH SAID CHANNELS IN SAID THIRD REGENERATIVE MASS INTO SAID CENTRAL COMBUSTION SPACE AND OFF-GAS FROM SAID CENTRAL COMBUSTION SPACE IS PASSED THROUGH THE CHANNELS OF EITHER THE FIRST OR THE SECOND REGENERATIVE MASS. 